Why unplugging the 02 sensor makes my 3.2 run smoother..
 

I replaced my 02 sensor a few months ago and recently noticed that if unplugged, the car ran smoother in general, no flat spots upon revving. Just a few notes, I did check all vaccum lines, adjusted valves, new sparkplug cables and adjusted base idle. Maybe running rich, although it doesn't smell like it.

Thoughts?


Serge

It goes into default mode which is richer and generally runs better since these cars were pretty lean originally.

Does the idle drop when you remove the oil cap? If not, you may still have a vacuum leak.

Or the O2 sensor is dead.

Just a guess since I am not the engineer who wrote that software.

It is because the feedback loop is broken, and the ECU is no longer trying to adjust the mixture. It is working off a set fuel map and it runs better.

That for your the replies:

Yes the idle drops when removing oil tank cap. The original 02 had the same side-effects as the new one, that's why I changed it.

Generally as the engine warms up, the car runs good with the sensor connected, but does run better without it.

Serge

I noticed the same thing with mine until the sensor got good and hot.

What is your idle RPM with O2 sensor plugged and unplugged?

The idle remains the same under both circumstances.